[Tails-l10n] Release schedule for Tails 4.0

Hi,

it's very likely that I'll be the Release Manager for Tails 4.0.

Here's the schedule:

* 2019-10-10: build and upload 4.0~rc1

* 2019-10-11: test and release 4.0~rc1

* 2019-10-21: build and upload 4.0

* 2019-10-22: test and release 4.0

Dear testers, please let me know privately if you're available for
testing on October 11 and/or October 22. Thanks in advance!

Cheers,
--
intrigeri